EUV Resist Formulation Simulation for Pattern Edge Roughness
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Solution Overview
Problem
In EUV lithography, the low output of light sources and the trade-off between resist pattern edge definition and sensitivity make it challenging to form extremely fine patterns efficiently, leading to variations in pattern dimensions and reduced device yield due to probabilistic variations in photon noise and active species distribution.
Innovation Solution
A simulation method and resist material optimization approach that calculates latent images and probabilistic variations to minimize pattern edge roughness, using a chemical amplification-type resist material with a photo-acid-generating agent and photodecomposable quencher, and adjusting their concentrations to optimize pattern formation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output of EUV light source is increased, then the exposure time can be reduced, but it is difficult to increase the output due to current technological limitations
Solution Approach 1:
The patent changes the parameters of the resist material system by introducing a photodecomposable quencher with specific decomposition characteristics. This allows the resist to become more sensitive to EUV light, compensating for the low light source output without requiring an increase in EUV power. The decomposition rate of the quencher is carefully controlled to optimize the balance between sensitivity and pattern definition.
2Productivity
If the sensitivity of resist material is improved to compensate for low EUV output, then exposure time is reduced, but pattern edge definition and roughness deteriorate
Solution Approach 1:
The patent applies local quality by creating different functional zones within the resist material system. The photodecomposable quencher is distributed throughout the resist, but its decomposition is localized to exposed regions where EUV light is present. This creates a spatial differentiation where exposed areas generate acid for pattern formation while unexposed areas maintain quencher for suppressing unwanted reactions, thus improving both sensitivity and edge definition simultaneously.
Solution Approach 2:
The patent uses a composite resist material system comprising multiple components: base resin, photoacid generator, photodecomposable quencher, and optional additives. This composite structure allows each component to perform its specific function - the base resin provides structural integrity, the PAG generates acid upon exposure, and the photodecomposable quencher modulates the reaction based on light exposure. The synergistic interaction of these components resolves the contradiction between sensitivity and definition.
3Manufacturing precision
If probabilistic variation in photon distribution is reduced, then pattern dimension variation is minimized, but this requires massive trial runs and long simulation times
Solution Approach 1:
The patent performs preliminary action by conducting simulations to determine optimal resist formulation parameters before actual manufacturing. The simulation model predicts pattern formation outcomes based on resist composition, allowing researchers to identify the best combination of PAG concentration, quencher concentration, and other parameters. This preliminary optimization reduces the need for extensive trial-and-error experimentation and minimizes pattern dimension variation in subsequent manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly reduces pattern edge roughness and variation, enhancing the yield of semiconductor devices by efficiently optimizing resist material formulation and pattern formation conditions, even with low photon counts, thereby improving the practicality of EUV lithography.
Implementation Method 1
a photo-acid-generating agent which generates an acid by being radiated with EUV light
Implementation Method 2
a photodecomposable quencher which traps an acid generated by the photo-acid-generating agent, and decomposes by being radiated with EUV light
Data Source
AI summary
A method of simulating a resist pattern according to an exemplary embodiment includes a step (A) of calculating a latent image of a concentration of an active species in a resist film that has been radiated by a radioactive ray along a target pattern with respect to a radiation position of the radioactive ray, a step (B) of calculating a change rate of the concentration with respect to the radiation position at an edge of the target pattern on the basis of the latent image, a step (C) of calculating a probabilistic variation at the edge of the target pattern, and a step (D) of calculating a variation in pattern edge roughness from the change rate of the concentration and the probabilistic variation.